This project seeks to elucidate the mechanisms by which oral sensory and perceptual experience is generated. Since objective measurement of the various aspects of oral experience is fundamental to this effort, the selection and refinement of appropriate psychophysical methods is a primary and continuing project concern. Currently, the routine assessment of taste is carried out using aqueous solutions representing each of the four basic tastes. Measures include both (detection) thresholds and judgments of intensity for taste stimuli at higher, more commonly encountered levels of strength. Olfactory function is routinely assessed by tests of odor identification. Assessments of sensitivity to local pressure on the tongue and to variation in the temperature or the viscosity, of an oral bolus are also available. These methods, applied to the study of age-associated changes, have provided insights into basic mechanisms of normal chemosensory perception. Similarly, studies of oral sensory changes associated with oral or systemic disease, salivary gland dysfunction, therapeutic X-irradiation, eating disorders or as an isolated complaint can contribute to an understanding of the mechanisms by which the complex oral stimuli encountered in everyday life are perceived.